package com.dragon.datastructure.tree.trie;

import java.util.TreeMap;

/**
 * 设计一个支持以下两种操作的数据结构：
 * <p>
 * void addWord(word)
 * bool search(word)
 * search(word) 可以搜索文字或正则表达式字符串，字符串只包含字母 . 或 a-z   . 可以表示任何一个字母。
 * <p>
 * 示例:
 * <p>
 * addWord("bad")
 * addWord("dad")
 * addWord("mad")
 * search("pad") -> false
 * search("bad") -> true
 * search(".ad") -> true
 * search("b..") -> true
 * 说明:
 * <p>
 * 你可以假设所有单词都是由小写字母 a-z 组成的。
 * <p>
 * 来源：力扣（LeetCode）
 * 链接：https://leetcode-cn.com/problems/add-and-search-word-data-structure-design
 * 著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
 *
 * @author dragon
 * @since 2020/1/2
 */
public class WordDictionary {

    private Node root;

    private static class Node {
        boolean isWord;
        TreeMap<Character, Node> next;

        public Node() {
            isWord = false;
            next = new TreeMap<>();
        }
    }

    /**
     * Initialize your data structure here.
     */
    public WordDictionary() {
        root = new Node();
    }

    /**
     * Adds a word into the data structure.
     */
    public void addWord(String word) {
        if (word == null || word.trim().length() == 0) {
            return;
        }
        Node cur = root;
        for (int i = 0; i < word.length(); i++) {
            char c = word.charAt(i);
            if (cur.next.get(c) == null) {
                cur.next.put(c, new Node());
            }
            cur = cur.next.get(c);
        }
        if (!cur.isWord) {
            cur.isWord = true;
        }
    }

    /**
     * Returns if the word is in the data structure. A word could contain the dot character '.' to represent any one
     * letter.
     */
    public boolean search(String word) {
        if (word == null || word.trim().length() == 0) {
            return false;
        }
        return search(root, word, 0);
    }

    private boolean search(Node cur, String word, int index) {
        if (index == word.length()) {
            return cur.isWord;
        }
        char c = word.charAt(index);
        if (c != '.') {
            if (cur.next.get(c) == null) {
                return false;
            }
            return search(cur.next.get(c), word, index + 1);
        } else {
            for (char key : cur.next.keySet()) {
                if (search(cur.next.get(key), word, index + 1)) {
                    return true;
                }
            }

            return false;
        }
    }
}

/**
 * Your WordDictionary object will be instantiated and called as such:
 * WordDictionary obj = new WordDictionary();
 * obj.addWord(word);
 * boolean param_2 = obj.search(word);
 */
